Image-taking lens unit

Abstract

An image-taking lens unit includes: a variable magnification optical system for forming an optical image of an object with a variable magnification; and an image sensor for converting the optical image into an electrical signal. The image-taking lens unit changes the shape thereof between a photographing state and a non-photographing state. The variable magnification optical system has a plurality of lens groups for performing magnification variation by changing intervals therebetween and a reflective surface for bending an optical axis. At least one of the plurality of lens groups is a movable group that moves during magnification variation. The reflective surface is kept in fixed position during magnification variation or focusing. In transition from the photographing state to the non-photographing state, at least the reflective surface moves so that at least part of the movable group is stored into a space left after the movement of the reflective surface.

1. An image-taking lens unit comprising: a variable magnification optical system for forming an optical image of an object with a variable magnification; and an image sensor for converting the optical image into an electrical signal; the image-taking lens unit changing a shape thereof between a photographing state and a non-photographing state,
 wherein the variable magnification optical system has a plurality of lens groups for performing magnification variation by changing intervals therebetween and a reflective surface for bending an optical axis and comprises at least two movable groups, at least one of which is located closer to an object side than the reflective surface and at least one of which is located closer to an image side than the reflective surface, at least one of the plurality of lens groups being a movable group that moves during magnification variation, the reflective surface being kept in fixed position during magnification variation or focusing, and 
 wherein, in transition from the photographing state to the non-photographing state, at least the reflective surface moves so that at least part of the movable group is stored into a space left after the movement of the reflective surface. 
 
   
   
     2. The image-taking lens unit according to  claim 1 ,
 wherein at least one of the plurality of lens groups is a fixed group that is kept in fixed position during magnification variation, the fixed group comprising a plurality of optical elements, between which the reflective surface is located, and 
 wherein relative position of the optical elements in the fixed group does not change during magnification variation or focusing but changes in the transition from the photographing state to the non-photographing state. 
 
   
   
     3. An image-taking apparatus having an image-taking lens unit in accordance with  claim 2 . 
   
   
     4. The image-taking lens unit according to  claim 1 ,
 wherein, where as the movable group, at least two movable groups are provided, at least one of which is located closer to an object side than the reflective surface and at least one of which is located closer to an image side than the reflective surface, where, of the movable groups located closer to the object side than the reflective surface, the one located closest to the reflective surface is referred to as an object side movable group, and where, of the movable groups located closer to the image side than the reflective surface, the one located closest to the reflective surface is referred to as an image side movable group, the object side movable group and the image side movable group move monotonously in magnification variation from a wide-angle end to a telephoto end, and conditional formula (1) below is satisfied:
   | T 1/ T 2|<1.9  (1) 
 
 
     where
 T 1  represents an amount of movement of the object side movable group in the magnification variation from the wide-angle end to the telephoto end, and 
 T 2  represents an amount of movement of the image side movable group in the magnification variation from the wide-angle end to the telephoto end. 
 
   
   
     5. An image-taking apparatus having an image-taking lens unit in accordance with  claim 4 . 
   
   
     6. The image-taking lens unit according to  claim 1 ,
 wherein, in magnification variation from a wide-angle end to a telephoto end, conditional formula (2) below is satisfied:
   0.1< L 1/ L 2<1.9  (2) 
 
 
     where
 L 1  represents a distance from a vertex of a most object side surface to a center of the reflective surface, and 
 L 2  represents a distance from the center of the reflective surface to a center of the image sensor. 
 
   
   
     7. An image-taking apparatus having an image-taking lens unit in accordance with  claim 6 . 
   
   
     8. The image-taking lens unit according to  claim 1 ,
 wherein conditional formula (3) below is satisfied:
   5< ft/fw   (3) 
 
 
     where
 fw represents a focal length of the entire variable magnification optical system at a wide-angle end, and 
 ft represents a focal length of the entire variable magnification optical system at a telephoto end. 
 
   
   
     9. The image-taking lens unit according to  claim 1 , wherein conditional formula (3b) below is satisfied:
   7 <ft/fw   (3b) 
 
     where
 fw represents a focal length of the entire variable magnification optical system at a wide-angle end, and 
 ft represents a focal length of the entire variable magnification optical system at a telephoto end. 
 
   
   
     10. An image-taking lens unit comprising: a variable magnification optical system for forming an optical image of an object with a variable magnification; and an image sensor for converting the optical image into an electrical signal; the image-taking lens unit changing a shape thereof between a photographing state and a non-photographing state,
 wherein the variable magnification optical system has a plurality of lens groups for performing magnification variation by changing intervals therebetween and a reflective surface for bending an optical axis, at least one of the plurality of lens groups being a movable group that moves during magnification variation, the reflective surface being kept in fixed position during magnification variation or focusing, 
 wherein, in transition from the photographing state to the non-photographing state, at least the reflective surface moves so that at least part of the movable group is stored into a space left after the movement of the reflective surface, and 
 wherein the movable group at least part of which is stored into the space left after the movement of the reflective surface is located closer to the object side than the reflective surface. 
 
   
   
     11. The image-taking lens unit according to  claim 10 ,
 wherein, in the transition from the photographing state to the non-photographing state, a movement direction of the reflective surface differs from a movement direction of the movable group at least part of which is stored into the space left after the movement of the reflective surface. 
 
   
   
     12. The image-taking lens unit according to  claim 10 ,
 wherein a movement direction of the reflective surface in the transition from the photographing state to the non-photographing state is parallel to a plane perpendicular to an optical axis located closer to the object side than the reflective surface. 
 
   
   
     13. The image-taking lens unit according to  claim 10 ,
 wherein the movable group at least part of which is stored into the space left after the movement of the reflective surface is located closer to an object side than the reflective surface and conditional formula (4) below is satisfied:
   2.5 <D/h< 7.3  (4) 
 
 
     where
 D represents an effective diameter of an most object side lens element, and 
 h represents a maximum image height on a light receiving surface of the image sensor (that is, one half of a diagonal line of a screen of the image sensor). 
 
   
   
     14. The image-taking lens unit according to  claim 10 ,
 wherein the movable group at least part of which is stored into the space left after the movement of the reflective surface is located closer to an object side than the reflective surface and that conditional formula (5) below is satisfied:
   0.35 <D/T air<1.00  (5) 
 
 
     where
 D represents an effective diameter of a most object side lens element, and 
 Tair represents a sum of variable air spacing located closer to an image side than the reflective surface. 
 
   
   
     15. An image-taking lens unit comprising: a variable magnification optical system for forming an optical image of an object with a variable magnification; and an image sensor for converting the optical image into an electrical signal; the image-taking lens unit changing a shape thereof between a photographing state and a non-photographing state,
 wherein the variable magnification optical system has a plurality of lens groups for performing magnification variation by changing intervals therebetween and a reflective surface for bending an optical axis, at least one of the plurality of lens groups being a movable group that moves during magnification variation, the reflective surface being kept in fixed position during magnification variation or focusing, 
 wherein, in transition from the photographing state to the non-photographing state, at least the reflective surface moves so that at least part of the movable group is stored into a space left after the movement of the reflective surface, and 
 wherein the variable magnification optical system includes: in order from an object side, a first lens group having a positive optical power; a second lens group having a negative optical power; the reflective surface; and a third lens group having a positive or negative optical power, the second lens group being a fixed group that is kept in fixed position during magnification variation, at least the first and third lens groups being movable groups. 
 
   
   
     16. The image-taking lens unit according to  claim 15 ,
 wherein the variable magnification optical system includes: in order from an object side, a first lens group having a positive optical power; a second lens group having a negative optical power; and a third lens group having a positive or negative optical power, the second lens group being a fixed group that is kept in fixed position during magnification variation, at least the first and third lens groups being movable groups, and 
 wherein the reflective surface is located in the second lens group. 
 
   
   
     17. An image-taking apparatus having an image-taking lens unit in accordance with  claim 16 . 
   
   
     18. An image-taking apparatus having an image-taking lens unit in accordance with  claim 15 .